Polyphase motor.



, ed By a l R/vfy S. SPARROW.

POLYPHAS OOOOO R.

APPLICATION PPPPPPPPPPPPPPP o.

wgz, Patented May16,1911.

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Simon Sparrow S. SPARROW.

Patll'ed May 16, 1911.

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ES. Parnu OFFE? SIMON SPRROW, OF ST. LOUIS, MISSOURI, ASSIGiNORl TO WAGNER ELECTRIC MANU- FACTUEING COMPANY, OF ST. LOUIS, MISSOURI, A CORPORATION 0F MISSOURI.

POLYPHASE MOTOR.

Specification of Letters Patent.

Patented May as, rari.

Application led April 30, v1911). Serial No. 558,644.

To all whom "Lt may concern:

Be'it known that I, SIMON SPARROW, a

- specification.

My invention relates'more particularly to polyphase induction motors having a single distributed winding of the closed coil type. Devices heretoforeproposed for diminishing the current taken by such polyphase motors at starting or 'for increasing the starting torque per ampere or for both-purposes, comprise auxiliary resistances or the like.

In my invention I not only reduce the current taken at starting but I also increase the torque per ampere while making use in my improved motor of only one winding on the induced member and of only the usual polyphase windings on the inducing member.

My construction greatly improves the space factor of the rotor thus increasing the running eiiiciencyof the machine while it enables me at the same time to secure the most desirable starting conditions.

Broadly speaking, my invention consists in providing the induced member of an ordinary polyphase induction motor with a winding comprising a plurality of elements, in permanently short-circuiting a part only of the total number of said elements and in providing means whereby all of the elements of my winding are short-circuited in any desired or convenient manner after the motor has reached a sufficient speed.

For the more complete understanding ofY my invention and its several advantages, reference is to be had to the following description taken in connection with the accompanying drawings in which Figure 1 is a diagrammatic representation of one'form of a four-pole three-phase motor embodying my invention and Fig. 2 is a complete diagram of the winding made use of on the induced member or" Fig. 1.

The stator 7 of Fig. 1 carries three fourpole windings 1--2, 3-4 and 5.-6 disposed in the slots 8 and so arranged thatthey can' 'rotor winding may have any desired pitch.

be suitably inter-connected to form a threelphase star or delta connected Winding as is well understood. The rotor 18 is provided with a four-pole drum winding 10 located in slots 9 and comprising a plurality of 60 elements. A suitable number of points of thls winding are connected to contacts 11 by leads 20 and a conductor 12 is so disposed that it can be brought into contact with all ,i

of the points 11 thus short-circuiting every elementof the rotor Winding. A number of elements of the rotor winding are permanently shortcircuited by means of the conductors 13.

A diagram of the rotor winding 10 is shown in Fig. 2. The winding shown consists of 23 elements or coils with two active conductors per coil located in 23 slots. The

Apermanently short-circuited pairs of active conductors 17 are distinguished by black dotsv whereas those pairs of active conductors which become directly short-cin.. cuited when the conductor 12 is moved into contact with.points 11 are distinguishedl by circles. Thevshort-circuiting device 12 may be moved into contact with all the points 11 or only with such of said points as are not permanently short-circui'ted by the conductors 13. I prefer the'former arrangement. It will be understood ythat my The winding shown in the figures has. a pitchnearly equal to the pole, pitch; a smaller or greater pitch may, however, be used. yIt is advisable to distribute the permancntly short-circuited elements throughout-'the rotor Winding. 4,

` When my improved motor is at rest then the short-circuiting device 12 is notin electrical contact 4with the rotor winding 10H95 As soon as the statorwindings are connected to thepolyphase supply a large torque is developed owing to the presence of the distributed vand permanent short-circuits 13 while the 'motor takes little current. soon as a sufficient speed has been reached then the short-circuiting device 12 is brought into electrical contact with the points- 11 and themachine is ready to develop its maximum running torque.

bination with an inducing member adapted 11o y I.1,05 Having fully described my invention' Ato be energized by polyplmse currents, of an n testimony whereof, I'have hereunto set induced member having a single distributed my hand and affixed my seal in the presence closed coil Winding comprising a plurality of the two'subscribng Witnesses.

of elements, a number of said elements' be- SIMON SPARROW. [Le] ing permanently short-circuifed, and means Witnesses: for short-circuiting theremaining elements C. B. BENNETT,

of said Winding. A M. L. FRANKLIN. 

